1. Field of the Invention
The present invention relates to a power transmission mechanism for a motorcycle. In particular, the present invention relates to a mechanism in which an elastic member is interposed between a driven flange and a wheel.
2. Description of Background Art
In a power transmission mechanism for a shaft driving system, if rapid variations in the rotation of a driving shaft or a wheel are transmitted to each other, riding comfort is impaired. To overcome this deterioration in riding comfort, a mechanism in which an elastic member is disposed between a driven flange rotated by a driving shaft and a wheel is disclosed in Japanese Examined Utility Model Publication No. 5-44599 or Japanese Unexamined Utility Model Publication No. 58-116887.
Referring to FIGS. 6 and 7 of the present invention, the above-mentioned conventional mechanism of the above documents will be described. A recess 102 is shaped like a fan when viewed from the side. The recess 102 is formed in a wheel 101 which is rotatably mounted on a rear axle 100. A damper rubber 103 is fitted in the recess 102. Furthermore, a metal collar 104 is fitted in the center of the damper rubber 103.
In addition, a driven flange 106 is spline-fitted in a final gear 105 to which power is transmitted from an engine and a pin 107 which is fixed in the driven flange 106 is inserted into the metal collar 104. Accordingly, the rotation of the driven flange 106 is transmitted to the wheel 101 via the damper rubber 103.
In the above-mentioned conventional mechanism, clearance must be provided between the pin 107 and the metal collar 104 in order to insert the pin 107 into the metal collar 104. Furthermore, since the driven flange 106 is freely movable in the direction of the rear axle 100, the driven flange 106 tends to move in the direction shown by an arrow in FIG. 6 when it is rotated. Therefore, in the conventional mechanism, there is a possibility that the pin 107 comes into contact with the metal collar 104. Accordingly, undesirable wear and sound is produced.
In order to solve the above problem, the present invention provides a power transmission mechanism for a motorcycle in which an elastic member is fitted in a recess formed in a wheel and a driven flange is connected to the elastic member to transmit power from an engine to the wheel via the elastic members, wherein the driven flange is divided into an engine side flange formed of a highly rigid material such as steel and a wheel side flange formed of a light material such as aluminum, and wherein the engine side flange is integrally connected to the wheel side flange with a fastening member.
While elastic members are provided with metal collars and driven flange side pins are inserted into the collars in a conventional power transmission mechanism for a motorcycle, in the power transmission mechanism in accordance with the present invention, the elastic members are not provided with metal collars and hence the pins do not contact the metal collars as is the case with the conventional power transmission mechanism.
A power transmission mechanism for a motorcycle in accordance with the present invention is suitable for a power transmission mechanism employing a driving shaft. In this case, power from the engine is transmitted to a final gear via a driving shaft and bevel gears and the above engine side flange is spline-fitted in the final gear.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.